Operating conditions
MLM/MLZ116 compressors can be operated at
nominal voltages as indicated below. Under-
voltage and over-voltage operation is allowed
within the indicated voltage ranges. In case of
risk of undervoltage operation, special attention
must be paid to current draw.
MLM/MLZ116 scroll compressors are available in
below motor voltages.
The recommended parallel assemblies design
from Danfoss Commercial Compressors have
been qualified to ensure there is no impact on
the compressor operating envelope.
More details can be found in the “MLM/MLZ116
application guidelines”.
Power supply
Compressor ambient
temperature
Operating envelope
Discharge temperature
protection
Refrigerants and
lubricants
MLM/MLZ116 scroll compressors can be applied
from -35°C to 55°C ambient temperature. The
compressors are designed as 100% suction
gas cooled without the need for additional fan
cooling.
Ambient temperature has very little effect on the
compressor performance.
For detailed information please refer to the
"MLM/MLZ116 application guidelines”.
The discharge gas temperature of each
compressor must not exceed 135°C.
DGT protection is required if the high and
low-pressure switch settings do not protect
the compressor against operations beyond its
specific application envelope.
More details can be found in the “MLM/MLZ116
application guidelines”.
Approved refrigerants and lubricants for MLM/
MLZ116 single compressors are also allowed for
parallel assemblies. For more details, please refer
to the "MLM/MLZ116 application guidelines".
The pump-down pressure switch must have a set
point slightly higher than the lowest compressor
safety pressure switch set point. The compressor
switch must never be bypassed and shall stop
all the compressors. The high-pressure safety
pressure switch shall stop all the compressors.
Whenever possible (i.e. PLC control) it is
recommended to limit the possibility of
compressor auto-restart caused by LP safety
switch settings to fewer than 3 to 5 times during
a 12-hour period.
Please refer to the “MLM/MLZ116 application
guidelines” for recommended settings.
High and low pressure
protection
Cycle rate limit
The system must be designed in a way that
guarantees a minimum compressor running time
of three minutes so as to provide for sufficient
motor cooling after start-up along with proper oil
return. Note that the oil return may vary since it
depends upon system design.
There must be no more than 12 starts per hour (6
when a resistor soft-start accessory is introduced);
a number higher than 12 reduces the service life
of the motor-compressor unit. If necessary, place
an anti-short-cycle timer in the control circuit,
then connect as shown in the wiring diagram
in the Danfoss Scroll compressor application
guidelines. A three-minute (180-second) time-out
is recommended.
Danfoss recommends a restart delay timer to
limit compressor cycling.
Motor voltage code 4
Nominal voltage
50 Hz
380-415 V - 3 ph
Voltage range
50 Hz
340-457 V
44
FRCC.PC.035.A4.02
Application Guidelines
Manifold compressors
